Polyurethanes (PUs) are excellent engineering materials but have poor oxidative/hydrolytic stability, while polyisobutylenes (PIBs) are excellent soft rubbers with outstanding oxidative/hydrolytic stability.
PUs containing exclusively PIB soft segments have been prepared previously. Early research was driven by the expectations that: (1) phase separation between the hard and soft phases would be excellent because of the incompatibility between the polar urethane hard segments and nonpolar PIB soft segments; and (2) the oxidative/hydrolytic stability of the products would be outstanding because of the saturated PIB segments.
PIB is used in numerous commodities, such as automotive inner tubes, wire insulators, etc., where oxidative/hydrolytic and chemical stability are required. While the oxidative/hydrolytic stability of these early PIB-based PUs was indeed outstanding, their mechanical properties were moderate to low because of the lack of hydrogen bonding between the hard and soft segments, and excessive incompatibility between the polar hard- and nonpolar soft segments.
Thus, there is a need in the art for polyisobutylene-based polyurethanes, polyureas and/or polyurethane-polyureas compounds that possess various desired mechanical properties in combination with various desired oxidative/hydrolytic stability